Notification Sending Apparatus, Notification Receiving Apparatus, Notification Delivery System Including These, and Notification Sending Method

1. A notification sending apparatus in a notification delivery system including the notification sending apparatus for sending notifications and a notification receiving apparatus for receiving the notifications, the notification sending apparatus comprising: at least one memory storing instructions; and at least one processor that executes the stored instructions to function as: a self notification identifier attaching unit configured to attach a self notification identifier to each notification, the self notification identifier having at least a sending ordinal position identification function; a sent notification identifier attaching unit configured to attach, to each notification, the self notification identifier attached to a notification that was sent immediately before each notification, as a sent notification identifier; a sending unit configured to send the notification receiving apparatus the notifications, each of which is attached with the self notification identifier and the sent notification identifier; and a re-sending unit configured, upon receipt of a re-send request including range specifying information from the notification receiving apparatus, to obtain at least one notification that has been sent and needs to be re-sent based on the range specifying information, and to re-send the at least one obtained notification to the notification receiving apparatus, wherein the notification receiving apparatus determines whether the sent notification identifier is the same as the latest self notification identifier stored in the notification receiving apparatus, and if the sent notification identifier is different from the latest self notification identifier, the notification receiving apparatus generates the range specifying information on the basis of the sent notification identifier and the latest self notification identifier.

2. The notification sending apparatus according to claim 1, wherein the at least one process further executes the stored instructions to function as: a sent notification identifier list holding unit where a list of the sent notification identifiers is stored as a sent notification identifier list; and an obtaining unit configured to obtain, from the sent notification identifier list, at least one sent notification identifier in a range specified by the range specifying information, as at least one self notification identifier attached to the at least one notification that has been sent and needs to be re-sent.

3. The notification sending apparatus according to claim 1, wherein the re-sending unit specifies the at least one notification that has been sent and needs to be re-sent on the basis of the at least one sent notification identifier obtained as the at least one self notification identifier by the obtaining unit.

4. The notification sending apparatus according to claim 1, wherein the notifications sent by the sending unit respectively contain notification contents, the notification sending apparatus further comprises a notification content list holding unit where a list of the notification contents included in respective notifications is stored as a notification content list, and the re-sending unit obtains, from the notification content list, at least one notification content to be included in the at least one notification that has been sent and needs to be re-sent.

5. The notification sending apparatus according to claim 4, wherein the at least one processor further executes the stored instructions to function as a storage cancellation unit configured, for at least a notification which does not need to be re-sent, to cancel storing of the notification content into the notification content list, wherein the re-sending unit cancels re-sending of a notification the notification content of which is unobtainable from the notification content list.

6. The notification sending apparatus according to claim 4, wherein the at least one processor further executes the stored instructions to function as a deleting unit configured to delete the notification content that satisfies a predetermined condition from the notification content list, wherein the re-sending unit cancels re-sending of a notification the notification content of which is unobtainable from the notification content list.

7. The notification sending apparatus according to claim 1, wherein the self notification identifier further has a self-other identification function.

8. A notification receiving apparatus in a notification delivery system including a notification sending apparatus for sending notifications and the notification receiving apparatus for receiving the notifications, the notification receiving apparatus comprising: at least one memory storing instructions; and at least one processor that executes the stored instructions to function as: a receiving unit configured to receive notifications, each of which is attached with a self notification identifier having at least a sending ordinal position identification function and is further attached with a sent notification identifier which is the same as the self notification identifier attached to a notification which is sent from the notification sending apparatus immediately before each notification; a received notification identifier holding unit where, every time the notification receiving apparatus receives a notification, the self notification identifier attached to the received notification is stored as a received notification identifier; and a first re-send requesting unit configured to send a first re-send request including first range specifying information to the notification sending apparatus upon receipt of a notification in a case where the received notification identifier held in the received notification identifier holding unit indicates a sending ordinal position temporally before a sending ordinal position indicated by the sent notification identifier attached to the notification received this time, wherein the notification receiving apparatus determines whether the sent notification identifier is the same as the latest self notification identifier stored in the notification receiving apparatus, and if the sent notification identifier is different from the latest self notification identifier, the notification receiving apparatus generates the range specifying information on the basis of the sent notification identifier and the latest self notification identifier.

9. The notification receiving apparatus according to claim 8, wherein even in a case where the received notification identifier held in the received notification identifier holding unit indicates a sending ordinal position temporally before a sending ordinal position indicated by the sent notification identifier included in the notification received this time, the first re-send requesting unit suspends sending the first re-send request including the first range specifying information to the notification sending apparatus for a predetermined period of time.

10. The notification receiving apparatus according to claim 9, wherein the at least one processor further executes the stored instructions to function as: a sent notification identifier holding unit where, every time the notification receiving apparatus receives a notification, the sent notification identifier attached to the received notification is stored as a sent notification identifier; and a second re-send requesting unit configured to send a second re-send request including a second range specifying information to the notification sending apparatus in a case where a new notification is received within the predetermined period of time and the self notification identifier attached to the new notification indicates a sending ordinal position temporally before a sending order position indicated by the sent notification identifier stored in the sent notification identifier holding unit.

11. The notification receiving apparatus according to claim 8, wherein the self notification identifier further has a self-other identification function.

12. A notification delivery system including a notification sending apparatus for sending notifications and a notification receiving apparatus for receiving the notifications, wherein the notification sending apparatus comprises: at least one memory storing instructions; and at least one processor that executes the stored instructions to function as: a self notification identifier attaching unit configured to attach a self notification identifier to each notification, the self notification identifier having at least a sending ordinal position identification function, a sent notification identifier attaching unit configured to attach, to each notification, the self notification identifier attached to a notification that was sent immediately before each notification, as a sent notification identifier, a sending unit configured to send the notification receiving apparatus the notifications, each of which is attached with the self notification identifier and the sent notification identifier, and a re-sending unit configured, upon receipt of a re-send request including range specifying information from the notification receiving apparatus, to obtain at least one notification that has been sent and needs to be re-sent based on the range specifying information, and to re-send the at least one obtained notification to the notification receiving apparatus, wherein the notification receiving apparatus determines whether the sent notification identifier is the same as the latest self notification identifier stored in the notification receiving apparatus, and if the sent notification identifier is different from the latest self notification identifier, the notification receiving apparatus generates the range specifying information on the basis of the sent notification identifier and the latest self notification identifier, and the notification receiving apparatus comprises: at least one memory storing instructions; and at least one processor that executes the stored instructions to function as: a receiving unit configured to receive notifications, each of which is attached with the self notification identifier and the sent notification identifier, a received notification identifier holding unit, every time the notification receiving apparatus receives a notification, the self notification identifier attached to the received notification is stored as a received notification identifier, and a re-send requesting unit configured to send the re-send request including the range specifying information to the notification sending apparatus upon receipt of a notification in a case where the received notification identifier held in the received notification identifier holding unit indicates a sending ordinal position temporally before a sending ordinal position indicated by the sent notification identifier attached to the notification received this time.

13. A notification sending method executed by a notification sending apparatus in a notification delivery system including the notification sending apparatus for sending notifications and a notification receiving apparatus for receiving the notifications, the notification sending method comprising the step of: attaching a self notification identifier to each notification, the self notification identifier having at least a sending ordinal position identification function; attaching, to each notification, the self notification identifier attached to a notification that was sent immediately before each notification, as a sent notification identifier; sending the notification receiving apparatus the notifications, each of which is attached with the self notification identifier and the sent notification identifier; and obtaining, upon receipt of a re-send request including range specifying information from the notification receiving apparatus, at least one notification that has been sent and needs to be re-sent based on the range specifying information, and re-sending the at least one obtained notification to the notification receiving apparatus, wherein the notification receiving apparatus determines whether the sent notification identifier is the same as the latest self notification identifier stored in the notification receiving apparatus, and if the sent notification identifier is different from the latest self notification identifier, the notification receiving apparatus generates the range specifying information on the basis of the sent notification identifier and the latest self notification identifier.